IntPtr bstr = Marshal.SecureStringToBSTR(password);
    
try
{
    // ...
    // use the bstr
    // ...
}
finally
{
    Marshal.ZeroFreeBSTR(bstr);
}

        public static byte[] CompressXML(string xml)
        {
            byte[] temp = Encoding.UTF8.GetBytes(xml);
            MemoryStream ms = new MemoryStream();
            DeflateStream ds = new DeflateStream(ms, CompressionMode.Compress);
            ds.Write(temp, 0, temp.Length);
            ds.Flush();
            ds.Close();
            return ms.ToArray();
        }
       
        public static string DecompressXML(byte[] data)
        {
            const int BUFFER_SIZE = 10;
            byte[] tempArray = new byte[BUFFER_SIZE];
            ArrayList tempList = new ArrayList();
            int count = 0, length = 0;

            MemoryStream ms = new MemoryStream(data);
            DeflateStream ds = new DeflateStream(ms, CompressionMode.Decompress);

            while ((count = ds.Read(tempArray, 0, BUFFER_SIZE)) > 0)
            {
                if (count == BUFFER_SIZE)
                {
                    tempList.Add(tempArray);
                    tempArray = new byte[BUFFER_SIZE];
                }
                else
                {
                    byte[] temp = new byte[count];
                    Array.Copy(tempArray, 0, temp, 0, count);
                    tempList.Add(temp);
                }
                length += count;
            }

            byte[] retVal = new byte[length];

            count = 0;
            foreach (byte[] temp in tempList)
            {
                Array.Copy(temp, 0, retVal, count, temp.Length);
                count += temp.Length;
            }

            return Encoding.UTF8.GetString(retVal);
        }